Variability in daily precipitation simulated by coarse scale climate models can be difficult to validate against station records because the level of variability in spatially averaged rainfall is not comparable to that of point rain-gauge observations.

Whilst for some regions, this can be overcome by using a large number of stations to give an areal average, for many regions the density or distribution of observations may not be sufficient to give a 'true' areal mean, and the result may mean that our baseline climate is biased.

The objective of this work is to estimate some of the properties of 'true' areal means, using only a small sample of stations. These estimates of areal precipitation variability can then be used to validate climate model daily precipitation simulations.